The present invention relates to a method of recording predetermined information signals onto a disk-type recording medium used for recording/reproducing apparatus such as hard disk drives.
Recording density of magnetic recording/reproducing devices has been increasing to realize larger recording capacity in a smaller body. In the field of the hard disk drive which is a representative magnetic recording/reproducing device, devices with a recording density per square inch of more than 3 G bit/inch2 (4.65 M bit/mm2) have already been commercialized. The development of the technology is so quick that, in several years from now, devices with the recording density per square inch of 10 G bit/inch2 (15.5 M bit/mm2) will have been put on the market.
The key factor behind this trend of increasing recording density is tracking servo technology used in the recording/reproducing head. With the current tracking servo technology for the magnetic recording media, regions of tracking servo signals, address information signals and reproduction clock signals are provided on the magnetic recording media at intervals of predetermined degrees (hereinafter, pre-format recording). A magnetic head reproduces these signals at predetermined intervals to confirm and modify its position and scan tracks accurately (Yamaguchi: Head Positioning Servo Technology for Magnetic Disc Drives, Journal of the Applied Magnetics Society of Japan, Vol. 20, No.3 pp 771-776, 1996).
The tracking servo signals, the address information signals and the reproduction clock signals work as references signals so that the magnetic head can scan tracks accurately. As such, during the recording of the signals, precise positioning is required. Thus, conventionally, a magnetic recording medium is set in a servo recording device and the pre-format recording is made by a magnetic head whose position is strictly controlled (Uematsu et al: The Status and Future of Mechanical, Servo and HDI Technologies, the Applied Magnetics Society of Japan, 93rd Seminar, 93-5, pp35-42, 1996).
However, the conventional method for pre-format recording conducted with the servo recording device specially made for the purpose has the following problems.
First, since the recording conducted with the magnetic head is basically a linear recording determined by the relative movement of the magnetic head and the magnetic recording medium, it takes a long time to make the pre-format recording with the conventional method. Furthermore, the cost of the pre-format recording made with the conventional method is very high since the expensive servo recording device for pre-format recording is needed.
Second, due to the spacing between the head and the medium, and expansion of the recording magnetic field caused by the poling of the magnetic head, transition of magnetization at the ends of the tracks lacks steepness. Inadequate steepness in the transition of magnetization obstructs the achievement of an accurate tracking servo technology.
To solve the problem of the conventional method of the pre-format recording using the magnetic head, the following methods have been suggested.
The Japanese Patent Laid Open Publication No. H07-78337 discloses a method in which a master medium and a slave medium (the medium to be recorded upon) are brought into contact with each other, and with a press contact means made with an elastic body, are pressed and thoroughly contacted.
The Japanese Patent Laid Open Publication No. H10-40544 discloses a method for transferring magnetic patterns onto a magnetic recording medium in which a master information carrier is created by forming a magnetic section composed of ferromagnetic materials on the surface of a substrate in a pattern corresponding to the information signals. The magnetic pattern formed on the master information carrier in a manner corresponding to the information signals, is transferred and recorded on a magnetic recording medium. The information transfer and recording is conducted by bringing the surface of the master information carrier into contact with the surface of a sheet or disk-type magnetic recording medium on which a ferromagnetic thin film or a layer coated with ferromagnetic particles is formed, and applying a predetermined magnetic field.
In recent years, disk-type recording media such as magnetic disks, photomagnetic disks and optical disks have been improved so as to have larger storage capacities in a smaller and thinner body. Against this background, the demand for high density recording media as mentioned above, has been increasing. To meet such demand, highly precise, reliable disk-type recording media are needed. Thus, it is urgent to produce very flat and smooth disk-type recording media whose surfaces do not attract any fine dust during the recording of information.
With regard to the disk-type recording media to which predetermined information signals are magnetically transferred and recorded as mentioned above, the master information carrier and the disk-type recording medium must be in tight contact with each other during the information transferring process in the manufacturing of the magnetic disks in order to precisely transfer the information of the master information carrier. Japanese Patent Laid Open Publication No. H11-25455 discloses an art related to such magnetic information transfer with which the tightness of the connection between the disk-type media is improved. With the method disclosed in the Publication, however, disks are not connected tightly enough since the disk-type master information carrier is provided with a hole, and during the process of making a hole, fine dust is created and tightness of the connection is hampered.
Considering this situation, the present invention aims to provide a method which achieves a quick, productive, and stable recording of high density information signals onto magnetic recording media, especially disk-type recording media such as build-in-type hard disk media, removable hard disk media, and large capacity flexible media.
In the recording method of the present invention, a disk-type master information carrier with predetermined information signals formed thereon is placed on top of a disk-type recording medium, and the information signals formed on the master information carrier are transferred and recorded onto the recording medium. When the master information carrier is placed upon and brought into tight contact with the recording medium, the surface of the master information carrier facing the recording medium becomes slightly concave in its center.